Process of solvent bonding polyethylene terephthalate copolyester fabrics with dimethyl sulfoxide



United States Patent 7 3,291,561 PROCESS OF SOLVENT BONDING POLYETHYL- ENE TEREPHTHALATE COPOLYESTER FABRICS WITH DIMETHYL SULFOXIDE Steven Abashian, Kinston, N.C., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., 21 corporation of Delaware No Drawing. Filed Apr. 17, 1963, Ser. No. 273,543 4 Claims. (Cl. 8-1301) This invention relates to an improved finishing treatment for synthetic linear copolyester fibrous material to improve the performance properties thereof.

A process is disclosed by Miller in U.S. Patent No. 3,053,609, issued September 11, 1962, to applicants assignee, for improving the aesthetics of fibrous material by treatment with specified one-phase liquid solutions containing a liquid vehicle, a latent fiber solvent soluble in or miscible with the liquid vehicle and an inert extender soluble in or miscible with the liquid vehicle. While the treatments disclosed in the patent provide useful improvements in body, liveliness, and dimensional stability of many types of fabrics, they do not provide useful fabrics with a high level of pilling resistance when applied to fabrics of copolyester fibers.

It is an object of this invention to provide an improved finishing treatment for bonding the fibers of copolyester fabrics at a series of small point-bonded sites. A further object is to provide a treatment for improving the pilling resistance of fabrics of copolyester fibers.

The above objects are accomplished by the improvement in the process of U.S. Patent No. 3,053,609 of treating textile fabric having at least a substantial proportion of synthetic linear condensation copolyester fibers, with a single-phase aqueous solution of dimethyl sulfoxide, or tetramethylene sulfone, and an inert extender, insolubilizing the extender and activating the di methyl sulfoxide or tetramethylene sulfone by heating the fabric to a temperature of at least 160 C., and then removing the extender and the dimethyl sulfoxide or tetramethylene sulfone from the fabric.

A preferred aqueous treating solution consists of 85% to 95% Water, between and 10% of dimethyl sulfoxide and between 0.2% and 2.0% of an inert extender such as polyethylene oxide. Small amounts of other materials may also be present which do not interfere with the effectiveness of the treatment.

By inert extender as used herein is meant a substance of sufiiciently high molecular weight or of such a complex structure that the substance is initially soluble or miscible with the aqueous medium to form a onephase solution but is subsequently capable of being insolubilized, for example, by heating to insolubilize an inert extender which has inverse solubility.

It is preferred to employ between 0.2 and 2.0% by Weight of the extender based on the total weight of the one-phase liquid solution. It is also preferred to employ an extender which is insoluble in the fiber solvent. Typical inert extenders which may be employed in preparation of the one-phase liquid solution include liquid and solid polyethylene oxides, polyalkylene ether glycols, sodium carboxymethyl cellulose, sodium alginate, methyl cellulose, and polyvinyl alcohol. Preferred extenders are the polyalkylene ether glycols (commercially available, for example, as Polyox WSR205, Polyox WSR-301, and polyethylene glycol 20,000 made by Union Carbide Corporation).

In practicing this invention, it is preferred to employ between 5% and 10% by weight of dimethyl sulfoxide or tetramethylene sulfone based on the total Weight of the one-phase solution. The use of 10% to about 50% based on the weight of solution, does not result in further improvements. Solvent concentrations in excess of 50%, while providing pilling protection, result in fabric stiffening.

The use of dimethyl sulfoxide or tetramethylene sulfone in the treatment of this invention gives unexpectedly superior results to the use of typical fiber solvents for synthetic polyesters, such as benzoic acid dichloroacetic acid trichloroacetic acid trifluoroacetic acid and trichlorophenol. The use of the halogenated acids results in severe fiber degradation while benzoic acid or trichlorophenol does not form the necessary one-phase aqueous solution due to their limited solubilities in Water. However treatment with dimethyl sulfoxide or tetramethylene sulfone is only effective for copolyesters. Homopolymers such as polyethylene terephthalate are not benefited by treatment with the compositions of this invention.

A typical process for treating fabric with the aqueous compositions in accordance with this invention is as follows:

(A) Prepare a one-phase liquid solution by dissolving the dimethyl sulfoxide or tetramethylene sulfone and an inert extender in the water and pad the solution on the fabric at room temperature;

(B) insolubilize the inert extender to form two (or more) phases with the phase containing the inert extender in contact with the fabric as a discontinuous coating preferably by drying the fabric;

(C) Activate the dimethyl sulfoxide or tetramethylene sulfone by heating the fabric to at least 160 C. to dissolve a portion of the fiber surface and redeposit the dissolved polymer to form fiber-to-fiber bonds preferably as part of the drying operation in step (B);

(D) Wash away both the extender and the dimethyl sulfoxide or tetramethylene sulfone and (E) Dry the fabric.

In order to accomplish step (C) when the fabrics are treated with the compositions of this invention it is essential that the temperature be at least 160 C. The treatment is ineffective at lower temperatures.

The aqueous solution may contain other materials for example small amounts of softeners, antistats, slickening agents, and the like providing they are carefully chosen in amount and composition so as not to disrupt the cooperating functions of the three main ingredients of the solution during application and processing on the fibrous material.

Typical of the synthetic polyester copolymeric materials which may be treated according to this invention include condensation products of ethylene glycol with a 90/10 mixture of terephthalic/isophthalic acids ethylene glycol with a 98/2 mixture of terephthalic/ 5-( sodium sulfo)isophthalic acids and ethylene glycol with a 90/10 mixture of terephthalic acid/hexahydroterephthalic acid.

The random tumble pill test, described by E. M. Baird, L. C. Legere, and H. E. Stanley, Textile Research Journal, 26, 701-735 (1956), is used to determine the pilling resistance of fabric samples. Six fabric test pieces, 4%; x 4 inch, are cut on a -degree bias across the full width of the fabric. The edges of the cut pieces are sealed with diluted Ubabond cement. The test pieces are examined after each 10 minutes of tumbling and given a pill rating of 1 to 5 where 5 shows no pilling and 1 has severe and unacceptable pilling.

The fibrous material to be treated in accordance with thi invention consists of, or comprises, staple fibers or yarns, or woven, knitted, or nonwoven fabrics therefrom.

Blends of fibrous materials containing fibers of synthetic polyester copolymers may be advantageously treated provided that at least of the fibers in the composition consist of copolyester fibers.

When treating fabric in accordance with this invention, the one-phase aqueous bonding solution is normally applied to the fabric as the last or essentially the last step in fabric finishing. The fabric is first prepared by weaving, knitting or any other conventional constructon, then it is dyed and finished by conventional means. Then the one-phase bonding solution is applied to the fabric with a take-up weight of about 100% to 300% by weight based on the weight of the fabric. However, standard textile finishes, such as softeners, antistats, and the like, may be applied to the fabric before or after bonding. However, these other finishes should not leave an impermeable film on the fibers that would prevent the bonding solution from penetrating the fibers. In addition to employing standard chemical finishing agents, there may also be employed mechanical finishing treatments before or after the point bonding in accordance with this invention. Such mechanical finishing treatments may include napping, brushing, teasing, shearing, fulling, semidecating, scouring, palmering, rotary pressing, calendering,-and the like.

Example I A solution is made by dissolving grams of polyethylene oxide having an intrinsic viscosity of about 15, as measured in methylene chloride, and 100 grams of dimethyl sulfoxide in 890 ml. of water, The above onephase finishing solution is padded onto a ZO-gram swatch of a fabric knit from fibers of a copolyester prepared from ethylene glycol and a 98/2 mixture of terephthalic/ ,5-(sodium sulfo)isophthalic acids. The fabric picks up about 200% of its own weight of solution. The treated fabric is force dried in an oven at 170 C. for 10 minutes. The fabric is then scoured, dried, and subjected to the random tumble pill test. After 10 minutes of testing, the treated fabric and an untreated control have a rating of 4.5; however, after 40 minutes, the control pills to an unacceptable extent and is rated 1.0, while the test fabric shows excellent pill resistance with a rating of 4.0.

When a fabric of polyethylene terephthalate is treated as above, the treated fabric has a rating of 1.5 after 40 minutes of testing, showing that the treatment is ineffective for the homopolymer material.

Example 11 Example I is repeated except that 10 grams of the polyethylene oxide, 50 grams of dimethyl sulfoxide and 940 ml. of water are used to prepare the one-phase liquid solution. The treated fabric has a rating of 4.5 after 10 minutes of testing and a. rating of 4.0 after 40 minutes of testing.

Relative viscosity determinations of treated fibers show no change from the original fibers, showing that the pilling protection is not due to polymer degradation.

Example III Example I is repeated except that 10 grams of the polyethylene oxide, 50 grams of tetramethylene sulfone, and 940 ml. of water are used to prepare the one-phase liquid solution. The treated fabric has ratings of 4.5 and 4.0 after 10 and 40 minutes of testing, respectively.

Example IV Ten grams of the polyethylene oxide of Example I and 100 grams of tetramethylene sulfone are dissolved in 890 ml. of water. padded onto a 20-gram swatch of a Woven fabric prepared from the copolyester of Example I. The fabric picks up 150% of its own weight of solution. The treated fabric i then treated as in Example I. After 40 minutes of testing, the treated fabric has a rating of 4.5, while an untreated control has a rating of 1.5.

Example V Example I is repeated except that the fabric is woven from fibers of a copolyester prepared from ethylene glycol The above one-phase solution is and a /10 mixture of terephthalic/hexahydroterephthalic acids. After 40 minutes of testing, the treated fabric has a rating of 5.0, while an untreated control has a rating of only 1.5

The chief advantage of this invention is the reduced pilling propensity of copolyester fabrics without adverse effect on fabric handle or significant loss in abrasion resistance. The treatments are effective with various fabric constructions, for example, knits and Wovens, prepared from copolyester fibers.

Since many diiferent embodiments of the invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited by the specific illustrations except to the extent defined in the following claims.

I claim:

1. In a process for bonding fibers of fibrous textile material only at isolated points on contiguous fibers by (A) applying to fibrous textile fabric, having at least a substantial proportion of synthetic linear condensation copolyester fibers, a single-phase solution of a liquid medium vehicle inert to the fibers, a latent solvent for the fibers and an inert insolubilizable extender which is a non-adhesive for the fibers;

(B) insolubilizing the inert extender to separate said solution into a plurality of phases, one of which phases contains the inert extender in contact with the textile fabric as a discontinuous coating; and

(C) rendering the latent solvent active to the extent that it softens the surface of the fibers of the textile fabric and renders them adhesive to each other at isolated points only, these points being ones at which fibers become contiguous; the surface of the fibers elsewhere having the inert extender therebetween rendering such surfaces non-adhesive to each other;

the improvement of applying to the copolyester fibers a single-phase treating solution essentially consisting of Water, dimethyl sulfoxide and an inert insolubilizing extender which is a non-adhesive for the fibers of the fabric, insolubilizing the extender and activating the dimethyl sulfoxide by heating the fabric to a temperature of at least 160 C., and then removing the extender and the dimethyl sulfoxide from the fibers, said copolyester being composed of 90% to 98% ethylene terephthalate units and the remainder of the copolyester being ester units selected from the group consisting of ethylene isophthalate, ethylene 5-(sodium sulfo)isophthalate and ethylene hexahydroterephthalate.

2. The process defined in claim 1 wherein said treating solution contains, based on the weight of solution, between 5% and 10% of dimethyl sulfoxide and between 0.2% and 2.0% of said extender.

3. The process defined in claim 2 wherein said extender is a polyethylene oxide.

4. The process defined in claim 1 wherein said treating solution is applied to the fabric to provide a take-up weight of about 100% to 300% based on the weight of the fabric.

References Cited by the Examiner UNITED STATES PATENTS 2,849,359 8/1958 Smith 156-308 3,053,609 9/1962 Miller 8-130.1 X 3,120,423 4/1964 Herschler et 211. 3,239,586 3/1966 Adams 8130.l X

FOREIGN PATENTS 609,947 10/ 1948 Great Britain,

NORMAN G. TORCHIN, Primary Examiner.

H. WOLMAN, Assistant Examiner. 

1. IN A PROCESS FOR BONDING FIBERS OF FIBROOUS TEXTILE MATERIAL ONLY IS ISOLATED POINTS ON CONTIGUOUS FIBERS BY (A) APPLYING TO FIBROUS TEXTILE FABRIC, HAVING AT LEAST A SUBSTANTIAL PROPORTION OF SYNTHETIC LINEAR CONDENSATION COPOLYESTER FIBERS, A SINGLE-PHASE SOLUTION OF A LIQUID MEDIUM VEHICLE INERT TO THE FIBERS, A LATENT SOLVENT FOR THE FIBERS AND AN INERT INSOLUBILIZABLE EXTENDER WHICH IS A NON-ADHESIVE FOR THE FIBERS; (B) INSOLUBILIZING THE INERT EXTENDER TO SEPARATE SAID SOLUTION INTO A PLURALITY OF PHASES, ONE OF WHICH PHASES CONTAINS THE INERT EXTENDER IN CONTACT WITH THE TEXTILE FABRIC AS A DISCONTINUOUS COATING; AND (C) RENDERING THE LATENT SOLVENT ACTIVE TO THE EXTENT THAT IT SOFTENS THE SURFACE OF THE FIBERS OF THE TEXTILE FABRIC AND RENDERS THEN ADHESIVE TO EACH OTHER AT ISOLATED POINTS ONLY, THESE POINTS BEING ONES AT WHICH FIBERS BECOME CONTIGUOUS; THE SURFACE OF THE FIBERS ELSEWHERE HAVING THE INERT EXTENDER THEREBETWEEN RENDERING SUCH SURFACES NON-ADHESIVE TO EACH OTHER; THE IMPROVEMENT OF APPLYING TO THE COPOLYESTER FIBERS A SINGLE-PHASE TREATING SOLUTION ESSENTIALLY CONSISTING OF WATER, DIMETHYL SULFOXIDE AND AN INERT INSOLUBILIZING EXTENDER WHICH IS A NON-ADHESIVE FOR THE FIVERS OF THE FABRIC, INSOLUBILIZING THE EXTENDER AND ACTIVATING THE DIMETHYL SULFOXIDE BY HEATING THE FAVRIC TO A TEMPERATURE OF AT LEAST 160*C., AND THEN REMOVING THE EXTENDER AND THE DIMETHYL SULFOXIDE FROM THE FIBERS, SAID COPOLYESTER BEING COMPOUND OF 90% TO 98% ETHYLENE TEREPHTHALATE UNITS AND THE REMAINDER OF THE COPOLYESTER BEING ESTER UNITS SELECTED FROM THE GROUP CONSISTING OF ETHYLENE ISOPHTHALATE, ETHYLENE 5-(SODIUM SULFO) ISOPHTHALATE AND ETHYLENE HEXAHYDROTEREPHTHALATE. 